Violence has fallen in Iraq since a wave of sectarian bloodshed in 2006 and 2007, but insurgents carry out frequent attacks on security forces and civilians in an attempt to undermine the Shiite-led government.

In north-west Baghdad, a parked car exploded outside a crowded restaurant in the Shiite neighbourhood of Shula, killing eight people and wounding 13, police said.

Elsewhere, a parked car blew up near the home of an adviser to Prime Minister Nouri al-Maliki, killing a civilian and wounding four people.

Earlier, explosions hit two adjacent homes of policemen in a Sunni neighbourhood, killing two and wounding nine people, among them three children. One of the policemen was killed and one was wounded.

A fifth attack targeted a police patrol in Baghdad, killing a policeman and wounding three officers.

Although the level of violence has dropped off sharply in recent years, deadly bombings are still common. On April 19, bombs blew up in 10 Iraqi cities, killing 30 people.

Some argue that the ongoing political impasse has opened the door to violence. The unity government headed by Mr al-Maliki, a Shiite, has been largely paralysed since the withdrawal of US troops from Iraq late last year.

There is mounting criticism of Mr al-Maliki within the ruling coalition, amid complaints that he is shutting out Iraq's two main minorities - Kurds and Sunni Muslims - in decision-making.